Simulation and theory of fluid–fluid interfaces in binary mixtures of hard spheres and hardrods

Abstract

We consider the free interface between demixed fluid phases in a mixture of hard spheresand vanishingly thin hard rods using Monte Carlo simulations and density functionaltheory. Both approaches treat the full binary mixture and hence include all rod-inducedmany-body depletion interactions between spheres. The agreement between theoretical andsimulation results for density and orientation order profiles across the interface isremarkable, even for states not far from the critical point. The simulation results confirmthe previously predicted preferred vertical (parallel) alignment of rod orientation tothe interface plane at the sphere-rich (sphere-poor) side. This ordering shouldbe experimentally observable in phase-separated colloidal rod–sphere mixtures.